docs: def angular_distance(km, lat, lat2=None):
      """
      Return the angular distance of two points at the given latitude.
  
      >>> '%.3f' % angular_distance(100, lat=40)
      '1.174'
      >>> '%.3f' % angular_distance(100, lat=80)
      '5.179'
      """
      if lat2 is not None:
          # use the largest latitude to compute the angular distance
          lat = max(abs(lat), abs(lat2))
      return km * KM_TO_DEGREES / math.cos(lat * DEGREES_TO_RAD)